ON THE MORNING of March 28th, the owners of newish Apple Watches in 19 countries woke up to find their timepiece was now a medical device. Two new features arrived. One monitors the wearer for an irregular pulse. The other allows a brief but detailed electronic portrait, or ECG, to be captured and inspected for signs of a common heart arrhythmia called “atrial fibrillation”, or AFib.
Americans have had these options since December, but their global expansion puts the technology squarely within the purview of public-health systems, which typically think carefully about how to screen for health conditions. The watch is also spurring debate about how doctors should handle the AFib that it and other consumer devices, such as AliveCor, detect.
AFib is the most common cardiac arrhythmia and occurs when the heart’s upper chambers do not beat in a co-ordinated fashion. Blood can pool in parts of the chambers and form clots. Patients with AFib are five times more likely to have a stroke. They can be treated successfully with blood-thinners, but these carry risks, primarily excessive bleeding. AFib is thought to occur in 2% of the population. However, as the risk of suffering from it increases greatly with age, it will be rare in Apple Watch owners, who are younger, richer and healthier.
Jonathan Mant, a professor of...